The Internet is a global network of interconnected computers and computers networks that use a variety of different operating systems or languages, including UNIX, DOS, Windows, Macintosh, and others. To enable communication among these various systems and languages, the Internet uses a language called TCP/IP (Transmission Control Protocol/Internet Protocol). TCP/IP supports three basic applications on the Internet: transmitting and receiving electronic mail, logging into remote computers (the Telnet), and transferring files and programs from one computer to another (FTP or File Transfer Protocol).
A primary design goal of TCP/IP is to interconnect networks that provide universal communication services, i.e., an “internetwork”, or “Internet”. Each physical network has its own technology dependent communication interface, in the form of a programming interface, which provides basic communication functions running between the physical network and the user applications. The architectures of the physical networks are hidden from the user. Another goal of TCP/IP is to interconnect different kinds of physical networks to form what appears to the user to be one large network. The TCP/IP protocol suite is named for two protocols, Transmission Control Protocol (TCP), and Internet Protocol (IP). Another name for it is the Internet Protocol Suite. The more common term TCP/IP is used to refer to the entire protocol suite.
TCP is a transport layer protocol providing end-to-end data transfer. It is responsible for providing reliable exchange of information between two computer systems. Multiple applications can be supported simultaneously over a single TCP connection between two computer systems.
IP is an internetwork layer protocol hiding the physical network architecture below it. Messages exchanged between computers include a routing function that ensures that the messages will be correctly directed within the network to be delivered to their destinations. IP provides this routing function. An IP message may be called an IP Datagram.
Application Level protocols are used on top of TCP/IP to transfer user and application data from an origin computer system to a destination computer system. Such Application Level protocols are, for example, File Transfer Protocol (FTP), Telnet, Gopher, and Hyper Text Transfer Protocol (HTTP).
With the increasing size and complexity of the Internet, tools called navigators or navigation systems have been developed to help find information on the network. Early navigation systems include standards such as Archie, Gopher, and WAIS.
More recently, the navigation system widely known as the World Wide Web (“WWW” or “the Web”) has emerged. The Web is an Internet-based navigation system, an information distribution and management system for the Internet, and a dynamic format for communicating on the Web.
The Web seamlessly integrates information that has a wide variety of formats, including still images, text, audio, and video. A user of the Web with a graphical user interface (GUI) may communicate transparently with different host computers and different system applications (including FTP and Telnet), using different information formats for files and documents including, for example, text, sound and graphics.
A “Router” is a computer that interconnects two networks and forwards messages from one network to the other. Routers are able to select the best transmission path between networks. The basic routing function is implemented in the IP layer of the TCP/IP protocol stack, so any host (or computer) or workstation running TCP/IP over more than one interface could, in theory, forward messages between networks. Because IP implements the basic routing functions, the term “IP Router” is often used. However, dedicated network hardware devices called “routers” can provide more sophisticated routing functions than the minimum functions implemented in IP.